Natural gas is one of safe gases, and it contains no carbon monoxide and is lighter than the air. Once it leaks, it will diffuse upwards immediately and will not accumulate to form explosive gas. Its safety is relatively higher than that of other gases. The use of natural gas as energy can reduce the use of coal and oil, thus significantly improving environmental pollution; natural gas, as a clean energy, can reduce nearly 100% of sulfur dioxide and dust emission, 60% of carbon dioxide emissions and 50% of nitrogen oxides emissions, and contribute to reducing acid rain formation, alleviating the greenhouse effects of the earth, so as to fundamentally improve environmental quality. With the development of society, the use of natural gas needs to be saved because of the increasing number of people who use natural gas and the fact that natural gas is a non-renewable resource. In the prior art, the main way to save natural gas is to regionally stop the supply of gas at cities or residence communities, and there is not yet a mature technical limitation or prompt to households over-consuming gas of the energy-saving needs.